How to Make a Geo Faceted Cement Planter

Have you noticed that cement is having a moment in design and interiors right now? It's certainly my current craft medium obsession! Since making a set of cement coasters, I wanted to tackle a bigger project. In this tutorial, you'll learn how to make your own mold for a faceted planter, using cardboard and tape. It's a fun project involving mixing cement - and at the end you'll have an amazing cement planter with touches of gold.

1. Make the Pattern

Step 1

Download and print the following pattern. Print it out as a full page on A4 paper and cut out the blue triangles. If you print the pattern at 100 per cent in size, the big triangle should be 10cm wide and the small triangle should be 6cm wide. You can make the planter in a different size, but remember to make one triangle about 2cm bigger than the other.

Step 2

Use the big triangle in the template to design the pattern on the cardboard, drawing one triangle at a time. Each triangle is attached to the next one - follow the printed template to trace and place all 15 triangles in to their correct positions.

Step 3

When tracing around the cut shape, the pencil width may cause the lines to deviate a little. You might want to go over and straighten the lines with a ruler. This will help you later on for clean creases.

2. Cut Out the Mold Pattern

Step 1

Use your metal ruler and a utility knife to cut out the cardboard pattern shape. Hold the cutter perpendicular to the cardboard for clean cuts.

Step 2

Next, use your ruler and your cutter to score all the inner triangles within your template for the mold. Remember not cut all the way through to the bottom. I'm using packaging cardboard with three layers (two layers of thick cardboard paper and a curly layer in the middle, like a sandwich).

Cut the first layer and the middle curly one, but make sure you don't touch the bottom layer, as shown in the photo below.

Step 3

Use the smaller triangle template and repeat the same procedure to make an identical pattern in a smaller size.

3. Shape the Mold

Step 1

Open the creases and shape the mold with your hands. You will notice that there are five internal corners that look like five triangles are cut out of the shape. Join the sides of the 'missing triangles' and stick them together on the outside, with packaging tape.

Step 2

Repeat for the rest of the corners to complete your mold. Repeat for your smaller pattern.

Step 3

Add packaging tape on every folded edge of the mold and continue taping until you have secured every surface of the outer side. You need to do this in order to keep the cement inside the mold, but also to keep the shape in place when the moisture seeps through the cardboard.

For the smaller mold, tape the surface of the inner mold as well. Make sure you seal all the little edges and holes. Avoid using tape on the sides that touch the cement as the tape will stick to it.

4. Prepare the Mixture

Step 1

Place the cement powder in the mixing container and add water. For 1.5kg of cement, I used about 850ml water. However, you should follow the directions according to the manufacturer's instructions on your cement mix packet.

Step 2

Stir it up with the back of your paintbrush until it's all wet. The desired texture looks a lot like yoghurt. Make sure you work quickly. Rapid drying cement starts to set in about 10 to 15 minutes.

5. Fill the Mold

Step 1

When your mixture is ready, pour a small amount in the mold. Shake it a little to make the layer even.

Step 2

Fill the small mold with soil and place it in the middle of the big one, as demonstrated in the photo below. Use the rest of the cement mixture and carefully fill the area around the outside of small box.

Step 3

You need to weigh down the central smaller mold, as it tends to float to the surface of the mixture. I've used a heavy drinking glass. You can't leave the bottom of the mold standing on its own, so you could either place it in the center of a tape roll for support, or you could pop it in some soil in a pot to help it keep its shape.

Step 4

Leave the cement to dry for about two hours and then remove the soil from the inner mold. While you're waiting, you can clean your mixing containers while the cement is still wet. Just rinse with water and softly rub the surface with a sponge.

6. Remove the Cardboard

Step 1

[After how long] Use your utility cutter to make slits in the cardboard, following the main lines of the triangles. Then pull and remove it from the planter.

Step 2

Pull the inner cardboard mold from the middle of the planter and remove it completely.

You will notice that a large amount of paper is stuck on the outside of your planter. Bring your planter to the sink and hold it under running water for about a minute. Gently rub the paper with your fingers and it will slide off.

Step 3

Leave your planter to dry for about half an hour.

7. Smooth the Surface and Improve the Shape

Step 1

You will notice that the cement feels cold. This is because it has retained some moisture inside, making it the perfect time to make the final adjustments and tweaks to the shape. Remove any bumpy edges using the paper cutter.

As long as the cement retains the moisture, you can cut it like cheese. Correct any distortions in the planter and shave the cement away with your cutter to create clean lines and perfect angles.

Step 2

Use sandpaper to make the surfaces of the planter smooth. I actually liked the embossed pattern from cardboard's ripples, so I left them un-sanded. Make sure you smooth any ultra-sharp edges so it's safe to handle. You don't want to go cutting yourself on your planter!

Step 3

Use your big paintbrush to dust the planter and remove any small pieces from sanding. Leave your planter to dry for a further two hours or more. When the surface of the planter feels the same temperature as your environment, it should be well and truly dry. At this point it's important to ensure that your planter is totally dry, otherwise the paint won't adhere properly.

8. Finish with Paint

Use the gold paint and a small paintbrush to decorate your cement creation. I chose an on-trend geo pattern for my planter. Gold is a very strong color, so use it wisely with little dashes of paint to highlight the shape and create a beautiful contrast to the industrial cement surface.

Plant a Cactus or a Succulent

When the gold paint is dry, you might like to plant a cactus or a succulent. Just fill with soil and pop your plant inside. You could also use your cement planter as a decorative bowl - imagine it filled with a bunch of clementines!

In this tutorial, you learned how to make a mold for cement out of cardboard and create a faceted design. You also learned how to mix cement, fill the mold and give your final product a professional finish. Finally, I demonstrated how to enhance the surface of your creation by trimming, sanding and painting the cement.